package services

import (
	"context"
	"encoding/json"
	"fmt"

	"github.com/SherClockHolmes/webpush-go"
	"github.com/google/uuid"
	"go.uber.org/zap"
	"gorm.io/gorm"
)

// PushSubscription represents a Web Push subscription (v0.302 N1)
type PushSubscription struct {
	ID        uuid.UUID `gorm:"type:uuid;primaryKey;default:gen_random_uuid()" json:"id"`
	UserID    uuid.UUID `gorm:"type:uuid;not null;index" json:"user_id"`
	Endpoint  string    `gorm:"type:text;not null" json:"endpoint"`
	P256dh    string    `gorm:"type:text;not null" json:"p256dh"`
	Auth      string    `gorm:"type:text;not null" json:"auth"`
	CreatedAt string    `gorm:"default:CURRENT_TIMESTAMP" json:"created_at"`
}

func (PushSubscription) TableName() string {
	return "push_subscriptions"
}

// PushService handles Web Push subscriptions and sending
type PushService struct {
	db              *gorm.DB
	logger          *zap.Logger
	vapidPublicKey  string
	vapidPrivateKey string
}

// NewPushService creates a new PushService
func NewPushService(db *gorm.DB, logger *zap.Logger, vapidPublic, vapidPrivate string) *PushService {
	return &PushService{
		db:              db,
		logger:          logger,
		vapidPublicKey:  vapidPublic,
		vapidPrivateKey: vapidPrivate,
	}
}

// SubscribePush stores a Web Push subscription for a user
func (s *PushService) SubscribePush(ctx context.Context, userID uuid.UUID, endpoint, p256dh, auth string) error {
	sub := &PushSubscription{
		UserID:   userID,
		Endpoint: endpoint,
		P256dh:   p256dh,
		Auth:     auth,
	}
	if err := s.db.WithContext(ctx).Create(sub).Error; err != nil {
		return fmt.Errorf("failed to store subscription: %w", err)
	}
	s.logger.Info("Push subscription stored", zap.String("user_id", userID.String()))
	return nil
}

// SendPushToUser sends a Web Push notification to all subscriptions of a user
func (s *PushService) SendPushToUser(ctx context.Context, userID uuid.UUID, title, body, link string) error {
	if s.vapidPrivateKey == "" {
		return nil
	}
	var subs []PushSubscription
	if err := s.db.WithContext(ctx).Where("user_id = ?", userID).Find(&subs).Error; err != nil {
		return err
	}
	payload, _ := json.Marshal(map[string]string{
		"title": title,
		"body":  body,
		"link":  link,
	})
	for _, ps := range subs {
		subscription := webpush.Subscription{
			Endpoint: ps.Endpoint,
			Keys: webpush.Keys{
				P256dh: ps.P256dh,
				Auth:   ps.Auth,
			},
		}
		_, err := webpush.SendNotification(payload, &subscription, &webpush.Options{
			VAPIDPublicKey:  s.vapidPublicKey,
			VAPIDPrivateKey: s.vapidPrivateKey,
			TTL:             30,
		})
		if err != nil {
			s.logger.Warn("Failed to send push", zap.Error(err), zap.String("user_id", userID.String()))
		}
	}
	return nil
}